Sen. Bernie Sanders of Vermont is the longest-serving independent member of Congress in history. He has caucused with Democrats since his days as Vermont's lone congressman, beginning in 1991, but he considers himself a democratic socialist. As he launches his presidential campaign, here are some other things to know about the Vermont senator:

— #Fillibernie: Sanders gained Internet fame in 2010 with a nearly nine-hour Senate floor speech slamming a deal that included a tax-cut extension for the wealthy as "Robin Hood in reverse." The Senate video server crashed after Sanders' staff posted a livestream of his speech, known as the #Fillibernie on Twitter, on the Sanders webpage. That fundraising quarter, Sanders quintupled his campaign funds. Nation Books published his words in The Speech, with authorial proceeds to go to Vermont charitable, non-profit organizations.

— His family: Sanders is the son of a New York-born mother and Polish-Jewish immigrant father, who worked most of his life as a paint salesman. He has said his lower middle class upbringing in Brooklyn taught him what economic insecurity means to a family. He and his wife, Jane, have four children -- Levi, Heather, Carina, and David -- and seven grandchildren.

— Religious background: Sanders was raised Jewish and spent time living on an Israeli kibbutz after graduating from the University of Chicago. He now says he is not actively involved in organized religion. When it comes the impact of religion on his life, he said, "I find myself very close to the teachings of Pope Francis," and he described the pope as "incredibly smart and brave."

— Scandinavia influences policy thinking: He believes lessons can be learned from the Scandinavian approach to governing and public policy. Namely, he says the U.S. should adopt the following principles: Treat health care as a right, provide higher education for free, protect the environment and reduce childhood poverty.

— Odd jobs and early politics: Sanders worked as a carpenter, filmmaker, writer and researcher after moving to Vermont in the 1960s. He ran unsuccessfully for statewide offices several times in the 1970s as a member of the anti-war Liberty Union Party – the only party to which Sanders ever belonged – before his successful bid as an independent mayor of Burlington in 1981.

— Recording artist: Sanders admits he can't carry a tune, but that didn't stop him from becoming a recording artist. Tracks that he recorded in 1987 with the former White Crow Studios -- a studio that recorded early music by the band Phish -- were re-released last year and are available on Amazon, iTunes, GooglePlay and CDBaby. The album, We Shall Overcome, features speeches about peace and justice delivered by Sanders as a choir sings 1950s and 60s protest songs.

Sanders speaks at a rally at the Vermont statehouse on July 1, 2016, in Montpelier, Vt., held to commemorate the implementation of the nation's first state law to require the labeling of foods made with genetically modified ingredients. Wilson Ring, AP

Sanders leaves the Vatican after the conference commemorating the 25th anniversary of "Centesimus Annus," a high-level teaching document by Pope John Paul II on the economy and social justice at the end of the Cold War, at Vatican City on April 15, 2016. Angelo Carconi, European Pressphoto Agency

Surrounded by members of the National Nurses United in "Robin Hood" hats, Sanders participates in a news conference on Capitol Hill on May 19, 2015, to discuss college tuition legislation. Jacquelyn Martin, AP

Vermont's top political figures, from left, then-senator James Jeffords, Sanders, Sen. Patrick Leahy and then-governor Howard Dean have a toast of milk as they celebrate the passing of the Northeast Dairy Compact in Montpelier, Vt., on Nov. 22, 1999. Toby Talbot, AP